ISO Water Resistance Standards

The "Water Resistant" mark has come to replace the "Water Proof" and is now described by the following ISO-Standard 2281:
Declaration on dial or back

NO DECLARATION

This model is NOT water resistant.
Any water contact should be avoided.

WATER RESISTANT

This model is resistant to minor and Accidental Splashes.
Greater water contact should be avoided.

WATER RESISTANT 30M
(3 ATM / 100 Feet) *

Protected in everyday life, bathing, accidental splashes, short swimming or car washing - it is resistant against perspiration, water vapor, rain drops.
It is tested for water resistance up to 3 ATM, and must be able to survive 30 minutes under water at a depth of 1 m (3 feet) followed by 90 seconds under a pressure corresponding to 30 meters

WATER RESISTANT 50M
(5 ATM / 160 Feet) *

Protected in everyday life, bathing, accidental splashes, short swimming, car washing, parachuting, hang gliding and skiing - it is resistant against perspiration, water vapor, rain drops.
It is tested for water resistance up to 5 ATM corresponding to 50 meters

WATER RESISTANT 100M
(10 ATM / 300 Feet) *

Protected in everyday life, swimming, snorkeling, mountain climbing, parachuting, hang gliding, skiing and all kinds of sports challenges
It is tested for water resistance up to 10 ATM corresponding to 100 m

WATER RESISTANT 200M
(20 ATM / 660 Feet) *

Protected in everyday life, free diving without scuba gear, and all kinds of water sports.
It is tested for water resistance up to 20 ATM corresponding to 200 m

WATER RESISTANT 300M
(30 ATM / 1000 Feet) *

Protected for scuba diving to a depth of 30 meters, for 2 hours.
It is tested for water resistance up to 30 ATM corresponding to 300 m

WATER RESISTANT 500M
(50 ATM / 1650 Feet) *

Protected for scuba diving to a depth of 50 meters, for 2 hours.
It is tested for water resistance up to 50 ATM corresponding to 500 m

* The metres value does not relate to a diving depth but to the air pressure
used in the course of the water resistance test. (DIN 8310, ISO 2281, NIHS 91-10)